This invention relates to a geosystem of the type which includes a plurality of layers, and which when prepared for use is positioned upon and in contact with the earth. According to another aspect, the invention relates to a method of forming such a layered geosystem.
In response to recently implemented environmental regulations, geosystems are now widely used on polluted areas of terrain as protective barriers to prevent contamination of ground water or nearby waterways. Such a geosystem can be used either to line containment cells or to cap a polluted, filled area.
In the case of a containment cell, which is essentially an excavated cavity in the earth, a geosystem is positioned at the bottom of the cell in contact with the earth. Such a containment cell can be used as, for example, a landfill as a depository for garbage or as a waste pond or canal in which various industrial waste products can be deposited. The geosystem in such a containment cell functions to prevent contaminated fluids, sometimes referred to as "leachate", from penetrating into ground water deposits or nearby waterways.
Where a geosystem is used as a cap, a polluted (i.e. garbage) area of terrain is covered with soil, which is then topped with the geosystem. The geosystem functions to prevent rain water from reaching the contaminated ground, so as to prevent percolation of water through the contaminated ground and to surrounding ground water deposits or nearby waterways.
Geosystems can include a substantially impervious membrane ("geomembrane") layer made of a plastic, for example, and typically also include additional layers such as fabric ("geotextile") and/or permeable net material ("geonet"). Geonet is placed above a geomembrane, and functions as a drainage layer in conducting a flow of contaminated fluids to a suitable collection system (i.e. a pipe network). Geotextile is used in geosystems for a variety of reasons. For example, a geotextile can be used as a separation layer between different layers of the geosystem or between a layer and soil, as a "cushion" or protective layer to protect other layers from damage due to rocks or other sharp objects, or as a drainage layer to conduct contaminated fluids therethrough due to the "wicking" action of the geotextile.
It is particularly desirable in the design of containment cells and filled in, capped areas to maximize slope of sidewalls of such containment cells and capped areas. This serves to maximize the volume available for storage of polluted materials for a given surface area of terrain, thus maximizing the cost effective use of available space.
Therefore, it would be desirable to provide an improved geosystem which is particularly adaptable to use on sloped areas of terrain.